Troubleshooting
GNS 480 (CNX80) Installation Manual560-0982-01 Rev A
4-3
Table 4-1. Troubleshooting Guide
Problem Possible
Cause
Solution
GNS 480 is not
receiving heading
from compass system
(ARINC 429 heading
input used)
•
GNS 480 ARINC 429 input not
configured correctly.
•
ARINC 429 input port speed not
correct
•
Wiring connections are incorrect.
•
Check ARINC 429 input port setting for
port that device is connected to.
•
Check ARINC 429 input port speed
setting for port that device is connected
to and verify that the speed is correct for
that device.
•
Check wiring.
GNS 480 is not
receiving heading
from compass system
(synchro heading input
used)
•
Heading Valid input invalid.
•
26VAC reference voltage is
incorrect
•
Wiring connections are incorrect
•
Check that heading valid input (P5-57)
is > 9 VDC. State of this input can be
checked in Ground Maintenance Mode.
•
Check that 26VAC, 400Hz reference is
supplied to P5-20,39
•
Check wiring.
GNS 480 heading
differs greatly from
compass system
(synchro hdg only)
•
Synchro X,Y,Z legs are crossed
•
26VAC reference Hi and Lo are
swapped.
•
26VAC reference supplied to GNS
480 is different than 26VAC
reference used by compass system.
•
Check wiring.
•
Check wiring.
•
Verify that GNS 480 and compass
system are using the same 26VAC
reference.
GNS 480 is not
receiving baro-
correction setting from
altimeter
•
GNS 480 baro pot input not
configured correctly.
•
GNS 480 baro pot input not
calibrated
•
GNS 480 is not the only device
tied to the altimeter baro pot
•
Check baro pot configuration in Ground
Maintenance Mode
•
Calibrate baro pot
•
Ensure GNS 480 is the only device
connected to the altimeter baro pot
Autopilot is not
getting GPSS/Roll
Steering data from the
GNS 480 (ARINC 429
Roll Steering used)
•
GNS 480 does not have a position
or flight plan entered.
•
GNS 480 ARINC 429 output not
configured correctly.
•
ARINC 429 output port speed not
correct
•
Wiring connections are incorrect.
•
Acquire GPS position and enter a flight
plan.
•
Check ARINC 429 output port setting
for port that autopilot is connected to.
•
Check ARINC 429 output port speed
setting for port that autopilot is
connected to and verify that the speed is
correct for autopilot.
•
Check wiring.
Autopilot is not
getting GPSS/Roll
Steering data from the
GNS 480 (RS232 Roll
Steering used)
•
GNS 480 RS232 output not
configured correctly.
•
Wiring connections are incorrect.
•
Ensure output port setting is MAPCOM
for port that autopilot is connected to.
•
Check wiring.
RMI pointer does not
indicate correctly
•
Desired RMI source has not been
selected
•
Wiring connections are incorrect.
•
Select desired RMI source from Nav or
GPS.
•
Check wiring
Tuning data not
updating DME
•
DME Select is not low
•
Wiring connections are incorrect.
•
Verify DME Select pulled low.
•
Check wiring.
Summary of Contents for GNS 480
Page 1: ...GNS 480 CNX80 Color GPS Nav Com Installation Manual September 2004 560 0982 01 Rev A...
Page 10: ...Table of Contents viii 560 0982 01 Rev A GNS 480 CNX80 Installation Manual NOTES...
Page 30: ...General Information 1 20 560 0982 01 Rev A GNS 480 CNX80 Installation Manual NOTES...
Page 126: ...Periodic Maintenance 6 2 560 0982 01 Rev A GNS 480 CNX80 Installation Manual NOTES...
Page 150: ...Appendix D Interconnect Diagrams D 2 560 0982 01 Rev A GNS 480 CNX80 Installation Manual NOTES...
Page 185: ......
Page 186: ......
